1. Field of the Invention
The present invention relates to a control device and method of controlling an internal combustion engine. More specifically, the present invention relates to a control device and method of controlling a port injection type internal combustion engine in which fuel is injected to an intake port.
2. Description of the Related Art
For example, Japanese Patent Application Publication No. 08-86234 (JP-A-08-86234) describes an engine air-fuel ratio control device that calculates a fuel injection amount during cold acceleration of an internal combustion engine, based on the amount of fuel adhering to the port. More specifically, the described control device calculates a fuel shortage amount Hm obtained by subtracting a function value H(tb), that is at acceleration timing tb, from an equilibrium adhesion amount, that is immediately before the acceleration timing. Then, the transient correction amount Kathos is increased by a value corresponding to the shortage amount Hm, thereby preventing the air-fuel ratio from shifting to the lean side when accelerating immediately after a cold start.
However, if an amount of shortage in fuel that has evaporated is compensated for by an increase in fuel injection amount, during cold acceleration, the amount of fuel adhering to the port is further increased. Also, the fuel that adheres to the intake port or the like during acceleration may later be supplied into the cylinder after acceleration. Consequently, when the amount of fuel adhering to the port increases, the air-fuel ratio controllability subsequent to acceleration deteriorates.